Remote-control system with supervisory means



April 29, 1952 HALLER 2,594,305

REMOTE-CONTROL SYSTEM WITH SUPERVISORY MEANS Filed June 15, 1945 4 Sheets-Sheet l INVENTOR. GEORGE L.HALLER Fl G. I BY ATTORNEY Ap 1952 G. L. HALLER REMOTE-CONTROL SYSTEM WITH SUPERVISORY MEANS Filed June 13, 1945 4 Sheets-Sheet 2 RADAR CO DED BEACON OUTPUT CODE SWI TC H l l- INVENTOR. GEORGE L.HALL E P ALA-@991 ATTORNEY April 29, 1952 G. HALLER 2,594,305

REMOTE-CONTROL SYSTEM WITH SUPERVISORY MEANS Filed June 13, 1945 4 Sheets-Sheet 3 CODING CIRCUITS BEACON RIG HT AZIMUTH LEFT INC.

RATE OF FLIG HT DEC- INVENTOR. GEORGE L.HALLER +5 F G. 3 y

W A 2 /,,AJ,L

ATTORNEY (5. L- HALLER April 29, 1952 REMOTE-CONTROL SYSTEM WITH SUPERVISORY MEANS Filed June 13, 1945 4 Sheets-Sheet 4 FIG.4

E m m B R PULSE REPETITION F REQl EN CY 400 5OOY GOO FIGS .INVENTOR GEORGE L. HALLER Q/Lu ATTO R N EY Patented Apr. 29, 1952 REMOTE-CONTROL SYSTEM WITH SUPERVISORY MEANS George L. Haller, Dayton, Ohio Application June 13, 1945, Serial No. 599,295 2 Claims. (01. 343-) (Granted under-the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein maybe manufacturedand used by or for the Government for governmental purposes, without the payment to me of any royalty thereon. V

This invention relates to remote control radio systems and more particularly to a remote control system with known telemetering of selector position or telemetering proportional control indicating neutral balance of either operation side thereof.

The objects of the present invention comprise the provision of an improved system and method of remote control that is strongly positive in action under a wide range of atmospheric conditions; that is operable with extreme rapidity; that utilizes very accurate precision devices of a high degree of perfection; and that provides for an object in flight a repeat-back signal that informs a control station of the position of the object in flight.

With the above and other objects in view that will be apparent to those who are informed in the field of remote control radio devices, improved illustrative embodiments .of the present invention in the form of circuits and associated devices are shown in the accompanying drawings, wherein:

Fig. 1 is a diagrammatical illustration of an overall embodiment of the present invention in operation;

Fig. 2 is a circuit diagram of a signal-controlled part of the present invention that is operated through a relay stepper;

Fig. 3 is a modified circuit diagram of a signalcontrolled part of the present invention that is operated through a plurality of relays;

Fig. 4 is a fragmentary circuit diagram illustrating a proportionate-control system adaptaion of the present invention; and- Fig. 5 is a frequency or pulse-repetition-frequency response graph diagram of the signal control in the proportionate-control system.

Referring more particularly to Fig. l the remote control system that comprises the present invention includes a control station i, that, by means of signals radiated by an antenna 2, exercises operative control over a remote station 3, for example, an aircraft or the like. The equipment at the control station I functions as an interrogator and preferably comprises a usual combination of radio transmitter and receiver which indicate the azimuth and the elevation of the aircraft 3 by both reflected echo signals from the aircraft 3 at short range and at greater range by the stronger signals from a coded beacon 4 2 that is located in the aircraft 3 and shown in detail in Fig. 2.' The transmitter at the control station I is also provided with the usual means for modifying pulse-repetition rates therefromto provide a plurality of signals that are preferred for the satisfactory operation of the present invention. The equipment in the aircraft 3 preferably comprises the coded beacon 4. that acts as a transpondor in the reception and in the emission of signal from and to, respectively, the control station I and that is in electrical combination with a pulse-repetition-frequency selector 5 is interposed between the beacon 4 and a plurality of controls on the aircraft 3.

The relationship of the beacon 4 and the selector 5 is shown both in Fig. 1 and Fig. 2 of the drawings. The beacon 4, preferably in the aircraft 3, is of a usual type and comprises a receiving antenna 6 and a transmitting antenna 1. Referring now more particularly to Fig. 2, the output of the beacon 4 is disposed across an isolation stage in the selector 5, the return circuit being through ground. The isolation stage comprises an isolating electronic tube In. The grid of the tube [0 is provided with a negative bias through a resistor H by a direct current source, such. as battery 9, or the like. The plate of the tube In is provided with a positive voltage supply through the primary winding of a transformer I2 is connected through a battery I4 to ground. The positive post of the battery 9 and the negative post of the battery 14 are connected to the cathode of the tube l0 and to ground. In re-- sponse to signals from the control station I, the isolation stage conducts a signal from the beacon 4 through the primary winding of the transformer I2 to ground and prevents feed-back of signal into the beacon 4.

The primary winding of the transformer [2 passes the signal inductively from the isolation stage to aplurality of secondary windings of the transformer I2 which are connected individually across the grid-cathode circuits of a I corresponding plurality of detecting electronic tubes 20, 2| and 22 that convert alternating current of the signal from the beacon 4 into direct current for the operation of relays to be described hereinafter. The secondary transformer windings that are disposed across the grid-cathode circuits of the tubes 20, 2| and 22 are individually tuned by capacitors 23, and 24 and 25, respectively, to provide the selector 5 with a plurality of frequency selective filters. The tubes 20, 2| and 22 are provided with negative gridbias by means of batteries 26, 21, and 28,

3 respectively, and with positive plate bias by means of a battery 30. The positive post of the battery 28 and the negative post of the battery 30 are connected to the cathode of the tube 22 and to ground.

Signals from the tube 20 operate arelay Stepper 32 with its-associated notched or pronged stepper wheel 3| and rotating switch arms 33, 34, and that are operated from a common shaft that is indicated by a dash-line therebetween. The coding relay rotating switch arm 33 sweeps a desired plurality of signal contacts A, B, C, D, and E. The signal contacts A, B, C, D, and E individually determine the code of the signalthat is generated by the radar coded beacon 4 and that is emitted from the antenna 1 thereof and that. is received at the control station I.

The wheel 3| of the relay stepper32 preferably is notched or is provided with prongs or stops on its periphery that correspond with the number ofcontacts. that areengaged individually by the switch arms 33, 34; 01*35; Thewheel 3lis'geared with the rotating switch" arms 33, 33,, and 35' in any-desired manner and so that when the coding relay switch arm 33 'is on any one of the contacts A, B, C; D; or E, the functional switch arms 34 and 3.5 are. on corresponding contacts oftheir respective switchesthat are indicated by corresponding. letters that are primed and double primed, respectively,. for ease in association with the contacts that are engaged by' the switch arm 33.

The frequency selectortube 21 closes the relay 38 in its plate circuitupon the selective reception of" a signal ofia predetermined frequency-or pulse repetition rate from the beacon 4' and passing through itsv respective filter comprising the capacitor Ztand the associated secondary transformer winding. In a imilar manner, the tube 22 closes the relay 33 in its plate circuit upon. the selective reception of a predetermined signal that is of a frequency that differs from the frequencies that are passed to either of the tubes 20:0r 21 from its respective filter, comprising the capacitor 25 and they associated secondary transformer winding. The energization of the circuit through the relay 38- takes effect uponthe functional switch-arm contacting one of the channel contactsA, B, C, D or'E that is selected by the stepping relay 32; The: contact so. made'energizes another relay, or similar device in the aircraft 3 not shown for any suitable control purpose. 7

The remote control system that is disclosed herein preferably is an extension of a usual radar system wherein a plurality-of controlfunctions are provided for and made available for use. In conformity with the present invention, these. control functions. are under the substantially complete and positive control of the control station I.

The radar at the control station I may be air borne. or in a fixed location, as preferred, and is so modified that the: pulse repetition rate thereof can be changed at will in discrete steps. An illustrative group of signal rates per second may comprise pulse repetition rates of 700 for normal, 800 for causing the operation of the stepper relay. 32, 850 for the operation of the relay 38' and 900 forthe operation of the relay 39: The normal or neutral pulse repetition rate is. used preferably during the tracking of the aircraft 3 without the operation. of any controls. The. other pulse repetition rates are used'for applying controls over the flight course of the aircraft 3. The neutral pulse rate is selected so that a signal of that rate will not pass through any of the filters of the control equipment.

The radar beacon 4 in the aircraft 3 preferably is a substantially standard or known type of radar coded beacon and serves to aid in tracking theaircraft 3. The beacon 4 in the aircraft 3 is modified so that it responds to a signal at the pulse repetition rate of the radar at the control station I. The beacon 4 is connected to the system of; selective filters that are shown in Fig. 2, and which have previously been described.

The present system is limited to the number of discrete and separable frequencies which can be transmitted from the control station I to the aircraft 3 and also by the fact that the pulsed signal which originates from the radar at the control station I- is so rich in harmonics, that, if the control frequencies are extended to more than one octave, serious difiiculties may be encounteredin differentiating a frequency which is a harmonic of another. control frequency from that of the desired control. frequency.

The present invention. is directed toward the objective of extending. the. number of' control functions. by means-of. various combinations of a small number ofbasic pulsev repetition rates. Thesecombinations. preferably are used in time sequence. Two signals of different pulse repetitionrates preferably are not emitted simultaneously from the radar at the control station I.

Inv the operation of the system that is contemplated hereby, a predetermined pulse repetition rate of the controlling radar'at the control station I is derived. in the usual manner from the radar, codedi beacon 4 in the aircraft 3 and the return: signal-from the beacon 4 to the control station 1 iscontrolled by the position of the switch arm 33. The pulse repetition rate so derived from the beaconl" is. fedthrough the isolating. tube" I0. into. one of the three electronic tubeslll; 23, or 2.2..

The tube. operates. the stepper-relay 32 and the stepper. wheel; 3:1 with its. associated switches 33; 3'4, and 35, as previously described. The tube 2| operates the relay 38 and the tube 22 operates the relay 39'. The channel; controls. in the aircraft 3" are powered in. common through the relays 38 and 33 and the switch arms 34 and 35 from a -l-A power source, asshown, to energize relay systems that operate to a predetermined degree and in pairs or functions. The pairs of functions exercised by the control on the aircraft 3, may be, for example, up and down, right and left, accelerate and decelerate, and the like. A particular pair of functions isselected by the operation .of' the tube 23 and its associated stepper relay 32.

The circuits'thatare shown in- Fig. 2 of the accompanying drawings are arranged to provide dual "operationsof fivefunctions. The controls for carrying out the dual operations of'these five functions are of a type in which there is con.- trol in either of two opposite senses and between which there-is a neutral state. The five functions areillustrated by positions A, B, C, Dand E; A. B, C", D and E" and A", B". C", D" and E" swept respectively by switch arms 33, 34 and 35:

The" stepper relay- 32' is adapted for selecting accuratelya desired step'on the wheel 3i. The relative-position'of the-stepper relay 32 with respectto the'-wheel 3l=is-relayed back to the control station I continuously from the beacon d through its antenna 1 by providing an individual or unique radar code response for each position of the stepper relay 32 with respect to the wheel 3|. In the present system the radar beacon response is coded in some known manner and this coded response is received and recognized at the radar control station I. The coding of the beacon 4 is accomplished by means well known in the art and will provide either different numbers, spacing or lengths of pulses, or any combination thereof, as a returning transmission from the beacon 4 to the control station I. A particular adopted code serves to determine at all times the position of the stepper switch 32 with respect to the wheel 3|. The code is changed by means of the coding relay switch associated with the arm 33, which is adapted to change the coded response of the beacon 4 to any one of the five different codes indicated by the five different stops on or notches in the periphery of the stepper wheel 3! corresponding to the letters A-E, inclusive, that are contacted by the switch arm 33. A particular code response from the beacon 4 depends upon the position of the coding relay switch arm 33 on its contacts A-E, inclusive, which is mechanically fastened to and operated by the same drive as are the functional switch arms 34 and 35, as indicated by the dash line therebetween.

In an illustrative control operation, the controlling radio at the control station I would be caused to search until a beacon response was obtained. The signal pulse repetition rate would then be switched to that frequency which would be accepted by the tube and the tube 20 would function to operate the circuit of the stepper relay 32. This operation of the tube 20 would cause a change in the coded response of the beacon 4. This change would be immediately noticed at the control station I.

The coded response change at the control station I imparts the information that the target has a control system. The operator at the control station then gives alternate impulses of the neutral pulse repetition rate and of the pulse repetition rate that controls the stepper switch 32, until the stepper switch 32 arrives at the required functional position, as indicated by the proper beacon response received at the control station I.

Assuming, for purposes of illustration, that the circuits A, and A" that are contacted by the functional switch arms 34 and 35, respectively, control a mechanism that governs the up and down positions of the elevators upon the aircraft 3, and that the circuits B and B" that are contacted by the same switch arms 34 and 35 control another mechanism that governs the right and left positions of the rudder on the aircraft 3. When so arranged, if the operator desires to control the aircraft 3 in azimuth, he sends the proper series of signal impulses from the control-station I that are necessary to step the stepper switch 32 to its B position and the switch arms 34 and 35 to, their B and B positions, respectively, which are indicated as corrected by the coded response from the switch associated. with the switch arm 33 through the beacon 4 and that are received at the control station I. I

r If the operator atthe control station I desires to .turn the aircraft 3 toward theright, he

changes the pulse repetition rate of the signal that is emitted from the control station I from the neutral frequency to that frequencywhich energizes the filter circuit associated with the tube 2! so that it operates the relay 38. The operation of the relay 38 energizes the circuit connected to B which, in turn and through the proper channel operates the functional controls which in turn operate an automatic pilot, or the like, that cause the aircraft 3 to turn toward the right. In a similar manner, the changing of the pulse repetition frequency so that the tube 22 is energized, operates the relay 39 and energizes the circuit connected to B which causes the aircraft 3 to be controlled to the left.

Various modifications of the control systems that are disclosed herein will be apparent to those who are familiar with the general subject matter of the present invention. The number of control circuits that are installed and used in a particular system for operating desired controls at the aircraft 3 can be increased orv decreased within practical limits without depart-' ing from the scope of the present invention.

Amodification in the frequency selector 5 part of thepresent invention, wherein a plurality of relays operate to perform the function of the stepper relay 32, is illustrated in Fig. 3 of the accompanying drawing. In the circuit there shown, a coded beacon 43 that is provided with a receiving antenna 4| and a transmitting antenna 42 serves as a transpondor with respect to the control station I.

Thecontrol operating output from the beacon 4B is applied to an isolation stage comprising a transformer 43 and an amplifier tube 44. The grid of the amplifier tube 44, to which signal from the beacon is applied, is grounded through the secondary of the transformer 43.

Output from the tube 44 passes through series connected primary windings, of a plurality of frequency selective transformers 45-49, inclusive, that are individually tuned as shown to separate and distinct predetermined frequencies. Apositive direct current voltage source, such as the +3 battery terminal shown, or the like, applies positive plate voltage to the tube 44 through the primary windings of the transformers 45-49, inclusive.

Signals induced into the tuned secondary windigs of the transformers 45-49, inclusive, are applied to the grids of a corresponding plurality of detecting electronic tubes -54, inclusive, that convert alternating current of the signal from the beacon 4|] into direct current for the operation of relays receiving the outputs therefrom. The outputs of the tubes 50-54, inclusive, are fed to a corresponding plurality of the relay windings -59, inclusive, that collectively have one .terminal in common through which +B' battery supply is fed to the plates of the tubes 50-54, inclusive, as shown. Signals through the tubes 50-52, inclusive, operate locking relays through relay windings 55, 56, and 51, respectively, and signals from the tubes 53 and 54 operate relays associated with windings 58 and 59.

The circuit that is shown in Fig. 3 of the drawings operates somewhat as in the previously described circuit in that signals from the control station I, are intercepted by the receiving antenna 4| on the beacon 4D and cause the beacon 40 to apply signal through the tube 44 to the frequency selective transformers 45-49, inclusive. Signals from an. emitting beacon antenna 42, provide information to observers at the control station l;r egarding the azimuth, altitude and range of theaircraft 3, and regarding the operations of thecontrols on the aircraft 3.

The circuit in Fig. 3 is adapted for the use of five different signal tones .to which the five transformers 45-49, inclusive, are separately and individually capacity tuned, as shown. The conduction of these five separate signals through the tubes 56-54, inclusive, energize the relay windings 55-59, inclusive, respectively.

The relay windings 55, 56 and .51 are associated with locking relays that are .50 connected that if any one of these relays is energized, it will lock in and stay locked until one of the other two relays in this group is energized, at which time the energized one of the other two relays will stay locked.

The energizing of any one of the relay windings 55, 56 or 51 causes an individual and unique signal code to be transmitted from the beacon 4 by way of its antenna 42 for the purpose of indicating to an operator at the control station I which of the relay coils '55, 55, or 51 has been energized in response to signal from the control station I. The relay windings 55, 56 and 51 are, in and of themselves, preferably not adapted for directly causing the operation of the particular controls with which they are associated but are adapted for setting contacts through which the operation of the controls is accomplished by supplying current therefor from a suitable direct current source, such as a battery 6| or the like, upon the energization of either of the operative relay windings 58 and 59. The separate energization of the relay windings 58 and 59 supply current to actuate opposite functions depending upon the preset circuit connection of any one of the relay windings 55, 56 or 51, such as right and left, up and .down, accelerate and decelerate, and the like.

In the illustrative embodiment of the invention that is shown in Fig. 3, the energization of any or all of the relay windings 55, 56 and 57 preset contacts that establish pairs of circuits to the controls on the aircraft 3 without causing any alteration in the flight course thereof. A desired alteration in the flight course of the aircraft 3 is accomplished by the selective energization of either of the relay windings 58 or 59, that selectively applies electrical energy lag one or the other of the two members in each pair of circuits that are --establ-is-hed by the energization of any or all of the relay windings '5, 56 and 51.

The energization of the relay winding-s '55 establishes circuits to a controller, such as an automatic pilot or the like, preparatory to altering the flight course ofthe aircraft 3 in azimuth toward the right or left. The energization of the relay winding 56 establishes circuits to a controller that is operated in conjunction with an altimeter or the like, preparatory-to altering the flight course of the aircraft -3 in elevation, either up -or-down. The energization o'f the relay winding 5? establishes circuits to acontroller that is operated in conjunction with suitable means for causing 'a-c'hange in the-rate of flight, such as for increasing or decreasing the rate of fiigh'tof the aircraft 3. The actual alterations inthe flight courseyrateofifl-ight-or other change in the performance of the aircraft '3, is not accomplished until asignal is received. from the control station I thatcauses the'energization'of either the relay winding 58 or the relay winding '59.

Additional transformer-frequencyselector amplifier tube relay groups of components that are substantially duplications of the transformer 4-1,

amplifier 5.2 and relay winding 51 group that forms a part of the circuit'that is shown in Fig. 3, may be added to the present circuit for the operation of additional controls, if desired.

In the operation of the modification of the device that is shown in Fig. 3, let it be assumed that the object in flight is to be caused to turn to the left, gain altitude, and then to perform a third operation, such as to accelerate its rate of flight, or the like. Let it be assumed also that the filter secondary windings of the transformers 4.5, 46, 41, .48 and 49 are tuned to individually pass signals of different frequencies referred to hereinafter as signals 0, P, Q, X and Y, respectively, .and which signals cause the operation of the relays 55, 56, 51, 58, and 5.9. respectively.

In conformity with this assumption, the relay windings 55, 5.6, and 57 are energized by the reception .of the signals .0, P, and .Q, .and the relay windings 58 and 59 are energized by the signals X and Y, respectively, throughout. Each application of a signal X .or Y causes a predetermined change in the status of the aircraft 3,.suchas an elevational change in the units of substantially one hundred feet through the operation preferably of an altimeter, and an azimuth change in angle of flight of a predetermined number of degrees by operation preferably of an automatic compass controller.

In conformity with the above assumptions, the sequence of signals that would be emitted from the control station l O-X-P-Y-Q--X Y. The initial signal 0 would be conducted by the transformer 4.5 and would cause the tube .56 ,to energize the relay winding 55.

The energization of the relay winding opens contacts G and H and closes contacts I,.J, K, and L of the relay associated with the winding 55. The closing of the contact I applies ground through the resistor 66 to the plate of the selector tube 5:). The closing of the contact J causes the beacon 45 to emit a signal to the control station 1 indicating the energizationof the relay winding 55. The closing of the right and leftazimuth contacts K and L applies no power to operate the right and left controls with which they are connected but does set up the connections through which control actuating power can be applied thereto and hence the closing of the contacts K and L alone is ineffectual to change in azimuth the course of fiightof the aircraft 3.

The relay contact L is inoperative to cause the aircraft 3 to turn to the left until the arrival of signal of the frequency X. The'signal of frequency X passed through the transformer 48 causes the tube 53 to draw more B+ current through the relay winding58. lhe energization of the relay winding'5'8 closes a contact of a relay associated with the coil 58 and applies a prede termined voltage from the battery 5| through the relay contact L to an operative mechanism, not shown, that turns the rudder of the aircraft 3 so that the course of the aircraft 3 is changed toward the left preferably an angle of a predetermined number of degrees. The rudder of the aircraft 3 is normally positioned to cause the aircraft 3 to fly straight ahead in the absence of signal. This concludes the functional azimuth change in flight course of the aircraft 3 in response to the signal sequence -OX in the cited example.

Theaircraft 3 is then prepared .to change altitude by theemissionof a signal '.P of a predeterwould be in the order mined frequency from the control station I. The reception of signal P by the beacon 4D, energizes relay winding 56. The energization of the relay winding 56 causes the operation of the relay contacts that are associated therewith in a manner that is substantially a duplication of the operation of the relay contacts that have been described for the relay assembly that is associated with the relay winding 55. As in the previous example, the arrival of signal P and resultant energization of relay coil 55 sets up the connections for, but does not accomplish the operation of the elevator on the aircraft 3.

The aircraft 3 is then caused to gain altitude by the emission of a signal Y of a predetermined frequency that, in a similar manner, is induced through the selective transformer 49, and that causes the closing of the contact that is associated with the relay winding 59. The closing of the contact that is actuated by the relay winding 59 causes the application of the potential of the battery 6| across the relay contact M that is associated with the relay winding 56, whereupon the altitude of the aircraft 3 is increased to a desired extent that preferably is a predetermined limited unit number of feet, such as one hundred feet, or the like. The relay contact N is closed along with the contact M, and causes signal of a predetermined frequency or pulse repetition rate to be emitted from the antenna 42 of the beacon 40 and that is intercepted by the antenna 2 of the control station I to indicate the operation of the relay winding 56. This concludes the functional elevational change in flight course of the aircraft 3 in response to the signal sequence P-Y in the cited example.

The control of the rate of flight of the aircraft 3 is effected in a similar manner by operation of the relay winding 51 and of the desired relay winding 58 or 59 to decrease or to increase, re-

spectively, the rate of flight of the aircraft 3.

The aircraft 3 is returned to normal flight by the release of either of the operating relays 58 or 59 that is accomplished in any desired manner upon the arrival of the aircraft 3 at a preestablished unit change in elevation, azimuth or rate of flight.

Two or more of the circuits including the tubes 2| and 22 in Fig. 2, if preferred, may be combined into a proportional control system. By the proper selection ofthe values of the inductances of the transformer I2 and of the capacitances of the tuning capacitors 24 and 25, by shunting the capacitors 24 and 25 with suitable resistors, or by the use of other suitable known means, two filters are formed with overlapping characteristics so that within a certain range all frequencies are passed by both filters in varying proportions.

In such a proportional control system, a pair of overlapping filters receives a signal of variable pulse repetition rate, the neutral frequency of the signal is substantially the mid-frequency of the overlap, and the plate circuits of the tubes 2| and 22 would be adapted to proportional control by known methods.

A proportional control system that is contemplated herein may comprise a derived output in the form of the mechanical rotation of a shaft, in which event the rotation of the shaft would be a number of angular degrees from a zero or center position that is proportional to the variation of the pulse repetition frequency from the neutral frequency. In this adaptation,

and a decrease in the signal pulse repetition frequency would cause rotation of the shaft in the opposite direction.

One stage of a proportional control system is shown in fragmentary form in Fig. 4 of the accompanying drawings wherein components that are common to both Figs. 2 and 4 bear corresponding numerical designations that are primed in Fig. 4 and that are not primed in Fig. 2 for ease .of association therebetween. The platecathode circuit of the isolating electronic tube 10 has the primary winding of a transformer in series therebetween. Two secondary windings of the transformer 65, together with their tuning capacitors 66 and 6?, provide a pair of frequency selective filters the ends of which are connected to the grids of a pair of gaseous electronic tubes 68 and 69. The direct current bias for these tubes 68 and 69 is obtained from a common bias battery 1'3 and from two potentiometers Ill and H which are connected across another battery 12. The plate current for the tubes 68 and 69 is furnished by an alternating current supply '14. The plate current for the electronic tubes 68 and 69 flows through direct current actuating motors l5 and 16, respectively. The motors l5 and 16 are so connected as to turn in opposite directions when energized. The direct current for the operation of the motors I5 and 15 is obtained by the rectifying action of the electronic tubes 68 and 69 on the alternating current source 74. A dotted line 19 shows a mechanical linkage which connects the potentiometers Ill and H, the motors 15 and 16, a sector ring 11 and a device to be controlled, in this case a rudder 18 part of the aircraft 3.

Additional pairs of secondary windings coupled to the primary winding of the transformer 65 may be provided, if desired, for the operation of additional controls, such as the elevators, velocity controls, and the like, on the aircraft 3. The additional pairs of such secondary windings that are inductively coupled with the primary winding of the transformer 65 are individually tuned to a further plurality of individual signals. The additional pairs of secondary windings on the transformer 65 are provided with additional pa' rs of electronic tubes in similar relation and other circuit elements such as are shown in Fig. 4.

The sector ring Tl, that is mounted upon and that rotates with the mechanical drive of the rudder 18, comprises a desired plurality of segments that are insulated from each other and that are individually connected to a beacon, such asbeacon 4 orthe like, to send signals to the control station I, as in the previously described adaptations of the present invention. The signals may comprise a desired sequence, such as those indicated as a line for a dot and a rectangle for a dash above the ring ll or the like, where the signal dot dash dot indicates the rudder in the neutral or straight ahead position, two dots and a dash indicates a turn to the left anda dash and two dots indicates a turn to the right in conformity with the letters L and R, respectively, and arrows on the rudder 18.

In the operation, of the present invention that is shown in Fig. 4 of the accompanying drawings, a signal is emitted from the control station I andis intercepted by the beacon 4 in the aircraft 3 as in the previously described forms of the invention. In response to the signal so inincreased signal pulse repetition frequency would cause the rotation of the shaft in. one direction ter'cepted, the beacon 6 applies a signal to the isolation stage tube 1 i! and to the transformer 65. The condensers 66 and 61 tunethe two parts of the secondary winding of the trans-former 55 to serve as filters in the inductive application of individual signals to the grids of the electronic tubes 68 and 69, respectively.

An example of a typical response curve of the two secondary windings of the transformer 65 is shown in Fig. 5, of the drawings. If the pulse repetition frequency is 400 cycles per second, as indicated by the line 65' in-Fig. .5, the secondary winding of the transformer 65 that is associated with the condenser 66, will pass a maximum voltage to the tube 68 and no voltage will be impressed on the grid of the tube .69 as indicated by the line 66'. If the pulse repetition frequency is 500 cycles per second, indicated by the line 80 in Fig. 5, equal voltages will be impressed on the grids of the two tubes 68 and 69. If the pulse repetition frequency is 600 C. P. S., as indicated by the line 61' in Fig. 5, no voltage will be impressed on the grid of tube 68 and maximum voltage will be impressed on the grid of tube 69.

At pulse repetition frequencies lying between 400 and 600 C. P. S., as, for example, at the dash line 8| in Fig. 5, the signal response voltage zy dominates the signal response :r-y, and proportional voltages will be impressed on the grids of the two tubes 68 and 69 as indicated by the response curves shown in Fig. 5. Bias potentiometers 10 and H, motors l and 115, sector ring 11 and rudder 18 are all connected mechanically to a common drive as shown by the dotted line 19 in Fig. 4. The motor I5, which is energized by plate current in tube 68 will cause counter clockwise rotation of the system shaft. The motor 16, which is energized by plate current in tube 69, will cause clockwise rotation of the system shaft. Bias battery 13 is so chosen that, with the mechanical system at neutral and equal voltages of a value indicated by the neutral pulse repetition frequency 500, as indicated by the line 80 in Fig. 5, applied to the grids of the tubes 68 and 69, there will be no plate current drawn by the tubes. This condition of neutral assumes that the potentiometers and H are at their mid-point and consequently battery '12 which is midtapped by battery 13 does not change the bias voltage value due to the battery 13.

Now assume that the pulse repetition frequency at the sending station is changed from 500 to a new value 550 as shown by the dash line 8| in Fig. 5. The grid voltage applied to the tube '68 will be decreased to the value ac-y and "the grid voltage applied to the tube '69 will be increased to the value y-z. The decrease of grid voltage on the "tube 68 will not eifect its condition of .zero plate current but the increase of .grid voltage on the tube 69 will cause it to pass plate current through the motor 16. "llhe .motor [6 will rotate until ithas changed the potentiometer 10 to such a value that it will increase the negative bias on the tube 69 .to a value which will no longer allow the flow of plate current in that tube. This mechanical motion of the motor 16 has also decreased the negative bias on tube 58 so that any increase I 'ei'ther'up pr down will cause the whole .mecha-nical system to seek a new unique balance that is associated with the new frequency. The proportionate control system that is so provided permits the disposition of the rudder 18 at any desired predetermined position between its zero setting, that causes the aircraft 3 to fiy straight ahead, and its full rudder position that causes the aircraft 3 to alter its course to a maximum extent toward the right or the left of its previous flight course.

In a proportional control device using a system of the described type, one of the difliculties of the coordination of the system is the corelationof the neutral control frequency with the neutral filter response of the controlled equipmentin the vehicle .or aircraft 3. Factors such as temperature, humidity and the like that are not identical in both the control and in the controlled equipment, commonly tend to destroy coordination. The remote control system that is disclosed herein permits the operator at the control station I to compensate properly for lack of coordination by adjusting at will the neutral control frequency that he is using to match that of the controlled equipment as indicated by the proper beacon response.

It is to be.understood that the particular circuits and the components and arrangements thereof that have been submitted herewith have been cited for the purposes of illustrating and describing suitable operative embodiments of the present invention and that various modifications, changes and substitutions may be made therein without departing from the present invention as defined by the claims that are appended hereto.

What I claim is:

l. A system for remotely controlling a number of devices, wherein each device has a plurality of alternative modes of operation; said system comprising a control station for sequentially transmitting a plurality of predetermined signals to a controlled station containing said devices; said controlled station including a receiver of said plurality of signals, a plurality of circuits coupled to said receiver, each of which is selective to a respective one of said predetermined signals, means coupled to a first portion of said plurality of circuits for conditioning for operation any one of said devices in response to the reception of a predetermined signal selected by said first portion of plurality of circuits, said first portion including more than one of said circuits, said conditioning means comprising a separate locking relay coupled to each circuit of said first portion, each relay having only one device associated therewith which is cpnditioned for operation by the actuation of that relay in response to the reception of the predetermined signal selected by the circuit to which that relay is coupled, said relays being connected .so that upon actuation of one relay said one relay is locked and a previously locked relay is released, and means coupled to each of the remaining portion of said plurality of circuits for operating that device which has been conditioned in a particular one of said alterna- -,tive modes in response to the reception of a particular predetermined signal selected by one of said remaining portion of plurality of circuits.

2. ,A system according to claim 1, further includingr..means at said controlled station for transmitting t said co tro stat o a distinc ccdels e alior a h re n cat v th relay being locked, and means at said control station for receiving said code signals.

GEORGE L. HALLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Hammond, Jr. Feb. 6, 1923 Number 14 Name Date Oswald July 15, 1924 Mirick Aug. 24, 1926 Mirick Dec. 18, 1934 Levy et a1. Aug. 4, 1936 De Ganahl Jan. 29, 1946 Clay Mar. 26, 1946 Dinga Apr. 2, 1946 'Finison Apr. 16, 1946 Wight et a1. May 27, 1947 

